FusionPBX prefers PostgreSQL to MySQL/MariaDB, but ClearOS offers MySQL/MariaDB by default.
"SQLite is a great choice for an embedded system or small business it should not be used for multi-tenant systems that will be used in production."
Source: https://www.fusionpbx.com/app/www/download.php
This makes sense with the typical WikiSuite users so let's try SQLite